It's basically the same principle behind making, say, the Millennium Falcon look believable and like it has real weight as it flies around. Whether it's a physical or CG model, it still needs to move in a certain way for it to look credible on screen.
Which is a pretty bad example, I'm afraid, because the type of spaceship movement that most people find "credible" -- e.g. having to bank into a turn and always fly nose-forward -- is based on the movement of aircraft in atmosphere and is totally wrong for the realistic motion of spacecraft in vacuum. There is absolutely no reason for a spaceship to bank. All it needs to do is rotate around its center of mass and thrust in a new direction. There's no reason it can't flip around and fly backwards or sideways or belly-first. Only a few productions have ever tried to get this right -- Babylon 5 being the only one I can think off offhand. Star Wars, though, blatantly tries to emulate the look of aerial dogfights in old war movies. And Star Trek has had an unfortunate tendency to mimic the Star Wars paradigm of ship movement ever since ILM was hired to do The Wrath of Khan. (Although that was based more on Age of Sail broadsides and submarine combat than aerial dogfights.)
A lot of times, what the audience thinks is credible is just wrong. I remember reading this book about ILM and its techniques, in the chapter on miniature photography, they discussed how there was a mathematical formula they could use to compute just how much they had to slow down miniature footage to make objects appear to fall at the same rate they would if they were full-sized... but how they usually ended up making it faster or slower than that because the mathematically correct answer didn't "look right." And that's just for mimicking how things would move under ordinary, real-world circumstances. When it comes to things that people have no everyday experience with, intuition is all but guaranteed to be wrong.